Low emissions combustion apparatus and method

ABSTRACT

Clean combustion and equilibration equipment and methods are provided to progressively deliver, combust and equilibrate mixtures of fuel, oxidant and aqueous diluent in a plurality of combustion regions and in one or more equilibration regions to further progress oxidation of products of incomplete combustion, in a manner that sustains combustion while controlling temperatures and residence times sufficiently to reduce CO and NOx emissions to below 25 ppmvd, and preferably to below 3 ppmvd at 15% O 2 .

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of application Ser. No. 11/149,959filed Jun. 10, 2005, which is based on and claims the priority of U.S.Provisional Application No. 60/579,135, filed Jun. 11, 2004 and U.S.Provisional Application No. 60/590,073, filed Jul. 21, 2004, the entirecontents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an apparatus and method of combustion thatproduces low emissions, carbon monoxide and oxides of nitrogen inparticular, and to progressing reactions to produce low intermediateproducts and byproducts.

2. Description of the Related Art

Energy conversion and chemical processing industries, seek toeconomically remove and/or produce specific chemical species. Unburnedhydrocarbons (UHCs), carbon monoxide (CO), and oxides of nitrogen (Nox)are three sets of chemical species which are commonly found in energeticfluids formed in hot chemical reactions, and more particularly, incombustion-based energy conversion industries.

Legislative authorities have periodically reduced allowable emissionlevels of these pollutants. Manufacturers of combustion-based power andother energy-conversion systems thus seek improved pollutant reductionsystems. Methods of reducing the emissions of these and other commonpollutants typically include,

(1) modifying the combustion process itself, e.g., tuning or configuringthe combustor/burner section of the system, or adding reactants toreduce the emissions (such as ammonia), and

(2) utilizing add-on technologies that effectively reduce or removepollutant species produced in earlier phases of the overall chemical orenergy-conversion process.

In typical combustion systems, control measures aimed at controllingeach of NOx, CO and UHCs can be counterproductive, thus increasing thecost and complexity of controlling overall emissions. For example, NOxemissions are understood to increase with, (1) increasing combustiontemperatures, becoming especially important above about 1300°-1500° C.,(2) with increasing residence time at the NOx-producing temperatures,and (3) with increasing concentrations of the effective oxidant,typically O₂, at the NOx-producing temperatures. Consequently, some ofthe most common in-situ or “in-combustor” strategies for reducing NOxlevels are informed by these understanding. They sometimes involveadding a diluent, such as excess air, exhaust gas, steam or water, toreduce undesirably high temperatures in the combustor. Furthermore, themore upstream the diluent is delivered to the combustor, the shorter theresidence time at NOx-producing temperatures. In some technologiesdiluent air and/or steam is premixed with the fuel and/or oxidantcontaining fluid to constrain the peak reaction or combustion flametemperatures. To reduce the amount of oxidant available that wouldoxidize nitrogen-containing compounds to form NOx, diluents other thanair, oxygen or similar oxidants are used.

It is commonly expected that CO and UHC emissions increase withdecreasing overall combustor temperatures and reduced residence times attemperatures high enough to promote UHC and CO oxidation to CO₂.Consequently, diluent-based NOx reduction strategies typically result insimultaneous undesired increases in the CO and UHC emissions in theenergetic or working fluid leaving the combustor, and vice versa.Furthermore while higher temperatures seem to promote UHC removal, COemissions tend to increase with incremental increases in temperature inhigh temperature ranges. This is especially a problem as higher turbineinlet temperatures are sought for higher efficiency in gas turbinesystems. The CO levels produced from systems with high combustorexit/Turbine Inlet temperatures are often substantially higher thanlegislatively allowed or desired emission levels.

Efforts to increase system throughput typically result in shorter hotresidence times, further raising UHC and CO concentrations. Rapidexpansion through a work engine or expander such as a turbine typicallyresults in rapid reductions in fluid temperature that “freeze” or“quench” the conversion of UHC and CO to CO₂, which can result in highUHC and CO emissions.

As in-situ methods typically have limited success in reducing emissions,they are often combined with add-on technologies that reduce or removepollutant species produced and present in the combustion product gases,e.g. selective catalytic reduction (SCR). Such add-on techniquestypically process the exhaust gases at low pressures. The utilizedadd-on technologies often substantially increase the volume, footprintand cost of the systems because of the high specific volume andcomparatively long kinetic time-scales of reactions that characterizeexhaust gases. Thus, even though these methods may successfully reduceemissions to acceptable levels, they often substantially increaseequipment, operation and maintenance costs.

SUMMARY OF THE INVENTION

One object of the present invention is configure and control thecombustion of a carbonaceous fuel using significant levels of aqueousdiluent to control combustion temperatures and the consequent productionof NOx, at the same time maintaining stable combustion through thestaged, progressive addition of air, fuel, and diluent to the hotcombustion gases.

Another object is to control the production of partial products ofcombustion such as CO, by the use of one or more equilibration stages,wherein the temperatures and residence times are controlled to promotethe conversion of CO to CO₂.

More generally, the objects of this invention are the minimization of byproduct species and partial reaction species, in a chemical reaction,using the steps of progressive, diluted primary reaction, followed bycontrol within equilibration stages. The combustion-based embodiments ofthe present invention exemplify methods of fluid delivery to the primarycombustion region and preferentially include equilibration regions orpassages.

The strategy of Progressive Combustion is employed within the primarycombustion region-to constrain combustion below temperatures that arenormally achieved in conventional combustion systems. Progressivecombustion is able to support stable combustion of common hydrocarbonfuels at average temperatures in the primary combustion region as low as650° C., well below the lower temperature limit of significant NOxformation of about 1300° C. Gases leaving the primary combustion regionof a combustor may have higher than acceptable UHCs and/or COconcentrations. Consequently, after primary combustion is accomplished,final burnout is achieved in equilibration regions where temperature ortemperature profiles are established that support rapid removal of UHCsand/or CO, decreasing their concentrations to levels not achievable inconventional combustion regions. These equilibration region controls maybe applied after progressive combustion, or after other primarycombustion techniques, whether conventional or novel.

The main design elements of Progressive Combustion include (1)streamwise distribution of fluid delivery and (2) improved mixing orpremixing. When applied to an exempliary combustor configuration, theProgressive Combustion principle results in (1) improved stability, (2)improved peak temperature control, (3) and improved chemistry/kineticcontrol and emission reduction, when compared with conventionaltechnologies. The methods may enable mixtures, conventionally consideredas non-flammable, to be burned in a controlled and stable fashionwithout blowout.

As energetic combusting fluid flows through the combustion chamber,mixtures of oxidant, fuel and diluent fluids are delivered to thecombustion chamber so that the delivered fluids interact with the hotcombusting fluid at a plurality of locations along the streamwisedimension of the combustor. The progressive combustion sequence isinitiated by energetic pilot fluids at the upstream end of thecombustion chamber, the outflow of the pilot being the inflow of thefirst combustion stage. At each stage, prescribed quantities ofuncombusted of oxidant, fuel and diluent fluid mixtures are delivered tothe combustion chamber, mixed together, and energized by heat from theoutflow of the previous combustion stage to temperatures that supporttheir ignition and the release of their chemical energies of combustion.The energetic fluids produced by this combustion form the outflow of thecurrent stage and the inflow of the next. In the design limit, thedistribution of delivery locations may be treated as a continuousdistribution rather than discrete locations.

Progressive Combustion generally applies to the upstream primarycombustion region, where most or a significant fraction of the totalfuel, air and/or water used is delivered to the combustion chamber, orwhere most or a significant fraction of the overall exothermic releaseof chemical energies occurs. Further downstream, equilibration regionsmay be used to further lower UHC and CO concentrations to target levels.In the equilibration regions, the thermodynamic equilibrium relationshipbetween CO, CO₂ and O₂, characterized by lower CO equilibrium levels atlower temperatures, is exploited. Consequently, after excess levels ofCO and UHC are oxidized to CO₂ in the primary combustion regions, thetemperature of the energetic fluid is controlled in one or more of theprovided equilibration regions. The fluid temperature within theequilibration region is controlled to be low enough to encourage COconcentrations in the hot combustion fluids to approach the lowerequilibrium levels, while being high enough to support high enoughreaction rates to the equilibrium level.

Accordingly, in the current invention, equilibration region(s) arepreferably provided or configured downstream of the primary combustionregion(s) to reduce the high CO emissions common in power systems. Theseequilibration regions (1) establish one or more desired equilibrationtemperatures, temperature ranges or temperature paths, and (2) provideone or more corresponding equilibration residence times sufficient toreduce the CO concentration to desired levels at the end of theequilibration residence times.

In some configurations, the fluid equilibration temperature isconfigured and/or controlled to between about 850° C. and 1450° C., andmore preferably between about 1050° C. and 1250° C. for typicalhydrocarbon-air based combustion systems, depending on the targetemissions levels. These temperatures are typically below temperaturesthat form significant NOx emissions. To achieve the same COconcentrations for different mixture conditions, users generally choosehigher equilibration temperatures as the concentration of excess oxygenin the system increases, as the carbon fraction of the fuel decreases,or as the fluid pressure in the system increases.

According to the combustion system objectives and/or design limitations,users preferably provide the equilibration temperature and appropriateequilibration residence time within the equilibration region(s) by oneor more energy transfer mechanisms. These energy transfer mechanisms mayinclude, but are not limited to:

Adding of further diluent to the combustion fluid flow;

Accelerating the combustion fluid flow;

Extracting energy from the combustion fluid flow using a turbine; and/or

Transferring heat from the combustion fluid flow by one or more ofconvection, conduction and/or radiation.

According to different energy-conversion system objectives and/or designlimitations, (e.g., the Turbine Inlet Temperature for gas turbines)users preferably add equilibration regions in sequential arrangementdownstream of progressive combustion regions. Additional emissionscontrol strategies may be incorporated into the overall system asdesired. Other chemical processes may also be conducted using similarmethods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically depicts an exemplary generalized embodiment of acombustor utilizing progressive combustion and equilibration strategiesto achieve emissions control.

FIG. 2 schematically depicts the longitudinal cross-section of anexemplary embodiment of an experimental combustor used to demonstrateaspects of progressive combustion and equilibration.

FIG. 3 is section A-A of FIG. 2, schematically depicting a transversecross-section through the stage 1 combustion region.

FIG. 4 is section B-B of FIG. 2, schematically depicting a transversecross-section through the stage 2 combustion region.

FIG. 5 is section C-C of FIG. 2, schematically depicting a transversecross-section through the stage 3 combustion region.

FIG. 6 shows graphical results of centerline temperature, COconcentration, and NO concentration for experiments performed in theexemplary embodiment of FIG. 2-FIG. 5.

FIG. 7 graphically shows the impact of the water-to-fuel ratio of thepilot on NO concentration in the exhaust fluids of the exemplaryembodiment FIG. 2-FIG. 5.

FIG. 8 schematically illustrates the impact of various delivery rateprofiles on progressive combustion stability, indicating stable,conditionally stable, and blowout regimes

FIG. 9 depicts the time-based effects of equilibration temperature on COand NO concentration in the product gases from the combustion of atypical hydrocarbon fuel with 5% of excess air and 3.15 times more waterthan the fuel mass.

FIG. 10 shows suggested equilibration temperatures at the expectedequilibration times for quickly reducing the concentration of CO incombustion product gases to target levels.

FIG. 11 schematically depicts an embodiment of the energetic sections ofa gas-turbine system comprising equilibration regions and using turbineexpanders for temperature control.

FIG. 12 is a graph of the appropriateness of suggested embodiments basedon the design temperature of selected components comprising thecombustion system.

FIG. 13 is a generalized Campbell diagram indicating regimes of flamestability, NOx formation and CO removal based on the relativeproportions of oxidant, fuel and diluent comprising the fluid mixtureinput to a typical hydrocarbon combustion system.

FIG. 14 is a graph of the results of a 1-dimensional simulation of aprogressive combustion and equilibration strategy in which progressivecombustion is caused to occur under slightly lean conditions, followedby the delivery of additional diluent to the equilibration regions ofthe system.

FIG. 15 is a graph of the results of a 1-dimensional simulation of aprogressive combustion and equilibration strategy in which progressivecombustion is caused to occur under slightly rich conditions, followedby the delivery of additional diluent and oxidant to the equilibrationregions of the system.

FIG. 16 schematically depicts a curvilinear temperature profile througha plurality of expanders with intermediate equilibrating residenceregions compared with a desired profile.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

U.S. Pat. Nos. 3,651,641, 5,617,719, 5,743,080 and 6,289,666 to Ginterare hereby expressly incorporated by reference herein. These teachdiluted combustion methods utilizing delivery of thermal diluent (suchas water) into a combustor to cool the combustion, reducing the use ofexcess dilution air. This invention further expressly incorporates byreference herein the following US Patent applications by Hagen et al.:

20050056313 Method and apparatus for mixing fluids of Mar. 17, 2005

20040244382 Distributed direct fluid contactor of Dec. 9, 2004

20040238654 Thermodynamic cycles using thermal diluent of Dec. 2, 2004and

20040219079 Trifluid reactor of Nov. 4, 2004. These applications teachfurther methods of delivering aqueous diluent with improved control overtransverse temperature profiles.

FIG. 1 is a generalized representative embodiment of a combustorapparatus utilizing the Progressive Combustion and Equilibration methodsto control emissions. The figure depicts Progressive Combustion within acombustor 1 comprising a combustion chamber 2 having a plurality ofstreamwise combustion regions in fluid communication, and having aplurality of discrete streamwise fluid delivery locations. Otherconfigurations may use continuous streamwise delivery or numerousdelivery locations providing pseudo continuous streamwise delivery.

The energetic combustor fluids F9 are characterized at the upstream endof the combustion chamber 2 by entering energetic pilot fluids F8.Downstream of the entrance of the pilot fluids F8 to the combustionchamber 2, prescribed quantities of oxidant F1, fuel F2 and diluent F3fluid mixtures are delivered to the combustor 1. After delivery,uncombusted fluids F4 comprising the oxidant F1, fuel F2 and diluent F3fluids are preferably mixed within one or more premixing regions 6,forming an uncombusted premix F7. The uncombusted premix fluid F7 ispreferably mixed with the energetic pilot fluids F8 to form an energizedcombustible mix F10. Energy available from the energetic pilot fluids F8contributes to the energizing the uncombusted premix F7, heating it totemperatures that support its ignition and the release of its chemicalenergies of combustion.

Delivering uncombusted premix fluid F7 is preferably combusted to formenergized combustible mix F10. This results in an increased mass, volumeand enthalpy flow of energetic combustor fluids F9 compared to theinitial inflow of energetic pilot fluids F8 into that combustion stage.Additional quantities of the uncombusted fluids F4 are preferablydelivered to the combustion chamber 2 in a similar manner, being addedat a plurality of locations along the streamwise dimension of thechamber 2. At each delivery location, uncombusted fluids F4 arepreferably combine and are delivered to mixing regions 6. The resultingpremix fluid F7 is then incorporated with energetic combustor fluids F9.These are at temperatures higher than that of the premix fluid F7, toform an energized combustible mix F10. The constituents of the energizedcombustible mix F10 will then be about at temperatures that supporttheir combustion. This method results in increased mass, volume andenthalpy flows of energetic combustor fluids F9 from one combustionstage into the next. In the design limit, the distribution of deliverylocations may be treated as a continuous distribution rather thandiscrete locations.

In some configurations, more than one of the stages in the ProgressiveCombustion sequence are fed by a common premixing region 7. Theproportions of the oxidant F1, fuel F2 and diluent F3 constituents beingfed to stages with a common premixing region 7 are about the same givingsimilar compositions.

In some configurations, no clear boundary 8, such as a physical wall,demarcates the premixing region 6. Consequently, there may not be adistinct separation of the premixing regions 6 from regions of highcombustion reactivity where the energetic combustor fluids F9 andenergized combustible fluids F10 are situated.

Throughout the progressive combustion sequence, the temperature,composition, and streamwise delivery profile of the fluids forming thepremix F7 may be controlled so that:

The temperature of the premix fluids F7 within the premixing region(s) 6are below temperatures that would support their spontaneous combustion.In configurations where there is a physical partition 8 between thepremixing region 6 and the combustion regions 40 to 48, such temperaturecontrol may prevent flashback. In configurations where the premixingregion 6 is within the confines of the combustion chamber 2 so that nophysical partition separates the premix fluids F7 from the highcombustion reactivity in fluids F9 and F10, such temperature controldeters premature combustion before delivered fluids F4 are completelypremixed. Combustion prior to full premixing is preferably avoided todeter formation of localized pockets or regions within the combustionregion where the chemistry of the oxidant:fuel:diluent mix could resultin undesired phenomena such as high temperatures regions, andconsequently, high NOx formation rates.

When the premix fluids F7 are combined with the energized combustorfluids F9, they form an energized combustible fluid F10 that has atemperature that is preferably high enough to support its spontaneousstable combustion.

The fluid composition including diluent are preferably configured toachieve a desired adiabatic combustion temperature. The resultingtemperature of the energetic combustor fluids F9 is preferablycontrolled within a certain prescribed temperature range. Examples ofsuch temperature constraints include avoiding temperatures that supporthigh NOx formation rates, or operating at temperatures within designlimits for system hardware. E.g., the maximum temperature of turbineblades further downstream or the maximum temperature of adjacentcombustor walls.

The end of the primary combustion region may be characterized by a finaldelivery stage, wherein the remaining uncombusted fluids F4 of theprogressive combustion sequence are mixed with the energetic combustorfluids F9, forming the primary combustion region's 3 last batch ofenergized combustible fluids F10.

With continued reference to FIG. 1, the energetic combustor fluids F12formed in the last stage of the progressive combustion sequence may atfirst have high levels of UHC and CO. e.g., due to an incompletebreakdown and oxidation of UHCs to CO and insufficient CO oxidation toCO₂. These combustor fluids F12 exiting the primary combustion region 3are preferably delivered to one or more downstream equilibration regions4. These preferably have sufficient residence time for concentrations ofspecies in the combustion product fluids F12 to approach the equilibriumlevels corresponding to the local temperature and pressure of thesystem.

If the combustion product fluids F13 leaving the first equilibrationregion 4 have CO concentrations above target levels, a fluid controldevice 10 may be used to adjust the temperature of the combustionproduct fluids F13. The temperature is typically lowered, thusestablishing new lower equilibrium level for CO concentrations toapproach. A second equilibration region 5 may follow the first fluidcontrol device 10. Here sufficient residence time may be provided toallow the concentration of species in the combustion product fluids F16to approach lower equilibrium levels corresponding to the lower localtemperature and pressure of the system.

The fluid control device 10 may also incorporate a means to deliverfluids F11, typically oxidant and/or diluent fluids to the combustionproduct fluids F13. In addition to changes in fluid temperature andspecies concentrations, the equilibrium change device 10 may also resultin a change in fluid pressure. If further reduction in the concentrationof CO or another intermediate reaction species is desired after thesecond equilibration stage 5, one or more further fluid control devices11 may be used to adjust one or both of the composition and adiabatictemperature of the combustion product fluids F16. Further diluent orheat exchange may be provided to control the hot combustion fluidtemperature within or at the system outlet. (e.g. establishing turbineinlet temperatures). E.g., the hot fluid entering the expander ispreferably delivered at a temperature of at least 950° C. Accordingly,at the end of the progressive combustion and equilibration sequences,the concentrations of select species, especially NOx, CO and UHCs, arepreferably reduced to target levels.

FIG. 2 shows a schematic diagram of a preferred embodiment of acombustor 1 which has been used to experimentally validate some featuresof the progressive combustion aspects of the current invention. Thecross-sectional area of combustion regions is preferably increased withstreamwise distance. E.g., FIG. 3-FIG. 5 show sections A-A, B-B and C-Crespectively of the combustor embodiment of FIG. 2. These components anddimensions are exemplary and not prescriptive of the methodsdemonstrated.

For example, in the proof of concept embodiment shown, the combustorcomprises five concentric steel fire tubes 12-16, each of the fourlargest tubes having inlets 17-20 for air-steam-fuel mixture. Here, thesmallest fire tube 12 is configured as the upstream pilot end of thecombustor 1, and the largest tube 16 as the downstream exhaust end ofthe combustor 1. The inner diameters of the fire tubes preferablyincrease. E.g. tubes 13-16 are about 1.3 centimeters (0.5 inches), 2.5centimeters (1 inch), 5.0 centimeters (2 inches), 7.5 centimeters (3inches), and 10 centimeters (4 inches). Their lengths are approximately17.5 centimeters (7 inches) for the pilot fire tube 12, 80 centimeters(31 inches) for the exhaust fire tube 16, and about 23 centimeters (9inches) for the other three fire tubes 13-15. A plenum cap 21 isattached to the downstream end of the four smallest fire tubes. Theinner diameter of the cap 21 may be configured equal to the innerdiameter of the fire tube 12-15 to which it is attached. The cap's outerdiameter preferably fits within the inner diameter of the next largestfire tube 13-16. A fire tube plate 22-25 is attached to the upstream endof each the four largest fire tubes 13-16 with a circular opening ineach plate configured to allow the clearance of the next smallest firetube 12-15. Fluid plenums 26-29 are preferably formed by the spacebounded by the wall of a fire tube and its corresponding cap, and thewall of the next largest fire tube and its corresponding plate.Air-steam-fuel mixtures F4 may be fed into each plenum through one ormore inlets. E.g., two inlets 17-20 in each plenum. The mixtures mayexit the each plenum through orifices 30-38 that deliver the mixture tothe combustion regions 39-48 that define the inner chamber of thecombustor 1.

While particular orifices have been shown, numerous streamwise deliverylocations may be used. Similarly, continuous streamwise delivery slotsor porous walls may be used. These delivery methods permit thedistribution of delivery locations to be treated as a semi-continuous ora continuous distribution.

At the upstream end of the combustor 1, an air-steam-fuel pilot mixtureF5 may be fed to the system first by delivery through the pilot inlets17 to the pilot plenum 26. From the plenum 26, the uncombusted pilotmixture F5 may be fed to the pilot combustion region 39 through aperforated steel fire tube 12. The wall of the pilot fire tube 12 isperforated with numerous orifices. E.g., about 80 fairly equally spacedorifices 30-31 of diameter about 1.6 millimeters (0.0625 inches). Thefluid mixture delivered through 40 of these orifices 30 may impinge onthe hot surface of an igniter 49. e.g. a glow plug. The igniter 49, maybe powered by an external electric power source 50. It may be insertedinto the combustor 1. e.g., through the opening of the 2.5-centimeterfire tube plate 22 and secured there by means of a flange 51.

The fluid mixture delivered by the remaining 40 orifices 31 ispreferably delivered to the pilot combustion region 39 downstream of thepilot igniter orifices 30 and the igniter 49. The fluid mixturesdelivered by first the 40 orifices 30 are heated as they flow betweenthe igniter 49 and the perforated pilot tube 12. These fluids arepreferably heated to temperatures that support their self-ignition. Thisforms a pilot combustion region 39 just downstream of tip of the igniter49. Remaining pilot fluid mixture is preferably delivered progressivelyto the pilot combustion region 39 and mixed with the product fluidsformed from the combustion of previously delivered pilot fluids. Mixingelements may be provided. E.g., A steel coil 52 may be wrapped along theinner wall of the pilot fire tube 12. This enhances mixing within thepilot combustion region 39 and has a thermal mass and bluntness thathelps act as a flame holder, thus improving the stability of the pilot.

The combustion product outflow F20 of the pilot combustion region 39 isequivalent to the inflow of the stage 1 combustion region 40. Anincreasing number of orifices are preferably configured along thestreamwise increasing direction. E.g., Four orifices 32, about equallyspaced at 90 degrees from each other in the same axial plane, permitfluid communication between the stage 1 plenum 27 and the stage 1combustion region 40. The air-steam-fuel mixture F4 is preferablydelivered to the stage 1 combustion region 40 through the four stage 1orifices 32. The delivered mixture is preferably energized by the inflowF20 to the stage 1 combustion region 40, sufficiently to support thecombustion of the uncombusted mixture delivered at this location.

The combustion product outflow F21 of the stage 1 combustion region 40is equivalent to the inflow of the stage 2 combustion region 41. Similarto Stage 1, about twelve orifices 33-35 allow fluid communicationbetween the stage 2 plenum 28 and the stage 2 combustion region 41. Thetwelve orifices 33-35 of stage 2 are may be divided into 3 sets of 4orifices. The four orifices comprising a set are preferably placed inthe same axial plane, preferably oriented with about an equal spacing of90 degrees from each other. Each orifice set may be axially separated byapproximately 3.8 centimeters at ambient conditions.

In this configuration, the orifices 33-35 protruded about 6 millimetersinto the stage 2 combustion region 41. Generally speaking, theair-steam-fuel mixture F4 delivered to the stage 2 combustion region 41through the stage 2 orifices 33-35 is energized by the inflow F21 to thestage 2 combustion region 41, supporting its combustion. e.g.,uncombusted mixture delivered through the four orifices 33 of the mostupstream of the three orifice sets, is energized by the inflow F21 tothe stage 2 combustion region 41. This forms the first combustion region42 of three stage 2 micro-combustion regions 42-44. The subsequentcombustion products from the first micro-combustion region 42 arepreferably used to energize the uncombusted mixture delivered throughthe second set of orifices 34. Likewise, the combustion products fromthe second micro-combustion region 43 of stage 2 are preferably used toenergize the uncombusted mixture delivered through the third set oforifices 35. The outflow of the third micro-combustion region 44 isequivalent to the overall combustion product outflow F22 of the stage 2combustion region 41.

The combustion product outflow F22 of the stage 2 combustion region 41is equivalent to the inflow of the stage 3 combustion region 45.Similarly with previous stages, eighteen orifices 36-38 allow fluidcommunication between the stage 3 plenum 36 and the stage 3 combustionregion 45. These eighteen orifices of stage 3 may be divided into 3 setsof 6 orifices 36-38. The six orifices comprising a set are placed in thesame axial plane, being oriented with about an equal spacing of 60degrees from each other.

In this configuration, each set of orifices is axially separated byapproximately 3.8 centimeters. The orifices 36-38 protrude approximately6 millimeters into the stage 3 combustion region 45. Generally speaking,the air-steam-fuel mixture delivered to the stage 3 combustion region 45through the stage 3 orifices 36-38 is energized by the inflow to thestage 3 combustion region 45, supporting its combustion. Morespecifically, uncombusted mixture delivered through the six orifices 36of the most upstream of the three orifice sets, is typically energizedby the inflow to the stage 3 combustion region 45, forming the first 46region of three stage 3 micro-combustion regions 46-48. The subsequentlycombustion products from the first micro-combustion region 46 arepreferably used to energize the uncombusted mixture delivered throughthe second set of orifices 37. Likewise, the combustion products fromthe second micro-combustion region 47 of stage 3 are preferably used toenergize the uncombusted mixture delivered through the third set oforifices 38. The outflow of the third micro-combustion region 48 isequivalent to the overall combustion product outflow F23 of the stage 3combustion region 45.

The combustion product outflow F23 of the stage 3 combustion region 45is equivalent to the inflow of the burnout and equilibration region 4.The 4-inch diameter fire tube 23 surrounding the burnout andequilibration region 4 is preferably insulated. E.g., it is wrapped withapproximately 1.5 inches of ceramic fiber insulation 53 to minimizeundesired heat losses from the burnout and equilibration region 4. Theoutflow of the burnout and equilibration region 4 is equivalent to theexhaust of the combustor 1.

FIG. 6 shows a representative centerline temperature profile measuredfrom experiments performed with the proof of concept combustorembodiment of FIG. 2-FIG. 5. TABLE 1 shows input conditions for theresults shown in FIG. 6.

TABLE 1 Fuel Propane - C₃H₈ Temperature of Delivery to Pilot 125° C.Temperature of Delivery to Stage 1 127° C. Temperature of Delivery toStage 2 136° C. Temperature of Delivery to Stage 3 128° C. RelativeStoichiometric Ratio of Pilot - Lambda-p 1.22 Relative StoichiometricRatio of Stage 1 - Lambda-−1 1.22 Relative Stoichiometric Ratio of Stage2 - Lambda-2 1.22 Relative Stoichiometric Ratio of Stage 3 - Lambda-31.22 Water to Fuel Ratio of Pilot - W-p 1.0 Water to Fuel Ratio of Stage1 - W-1 7.1 Water to Fuel Ratio of Stage 2 - W-2 7.1 Water to Fuel Ratioof Stage 3 - W-3 7.1 Ignitor Power 150 W Fraction of Total VolumetricFlow to Pilot 11% Fraction of Total Volumetric Flow to Stage 1 34%Fraction of Total Volumetric Flow to Stage 2 22% Fraction of TotalVolumetric Flow to Stage 3 33% Overall Water to Fuel Ratio - W-tot 6.3Overall Relative Stoichiometric Ratio - Lambda-tot 1.22 Total Flowrate150 slpm

With further reference to FIG. 6, after the pilot region, the averagetemperature during the progressive combustion sequence ranges from about650° C. to 950° C., with an average of about 800° C. Each minimum in thetemperature profile is located approximately 1 to 2 centimetersdownstream of the corresponding delivery location. The minima in theprofile are due to convective energy transfer from the energeticcombustor fluids to the recently delivered premix fluids. Temperaturesof the magnitude shown in FIG. 6 are significantly lower than thetemperatures that are conventionally believed to be necessary to achievestable combustion. Furthermore, such low temperatures are expected toresult in low NOx formation.

FIG. 6 also shows the NOx and CO concentrations in the burnout andequilibration regions of the combustor with the relative stoichiometricratio of the pilot, Lambda-p, set to 3.5. These results demonstrate theability to achieve CO and NOx concentrations of about 3 ppm or less forboth species. Low NOx levels are generally expected for such lowtemperatures. However, CO levels are commonly expected to be very highunder low temperature combustion conditions. Just downstream of the lastdelivery location at about 43 centimeters, CO levels are initially veryhigh, on the order of 100 ppmv to 1000 ppmv due to the incompleteburnout of recently delivered fuel. As one progresses downstreamhowever, CO levels fall significantly with an eventual asymptote ofabout 3.5 ppm. The results of this experiment demonstrate that very lowCO levels can be achieved with the implementation of the progressivecombustion method.

FIG. 7 shows the dependency of exhaust NOx levels to the water-to-fuelratio of the pilot, while keeping the inputs to the remainder of thesystem constant. As more water is added to the pilot the concentrationof NOx in the exhaust (downstream of the progressive combustionsequences) decreases. This is generally expected as more water resultsin a lower flame temperature in the pilot, resulting in lower rates ofthermal NOx formation. FIG. 7 also demonstrates for these conditions,most of the NOx in the system is likely formed in the pilot wheretemperatures are highest, suggesting that the progressive combustionsequence as demonstrated here, results in sub-ppm levels of NOx due tothe low temperature achievable during the combustion process.Consequently, sub-ppm levels of NOx may be achievable for the overallcombustor provided that it is configured with a pilot that has low NOxlevels.

FIG. 8 depicts an embodiment of the current invention configured andcontrolled with progressive delivering and combusting of an uncombustedfuel-oxidant-diluent mixture at five different mixture delivery rates.It shows the combustor fluid temperature, the CO concentration, andrelative fluid delivery rate versus progressive combustion along thestreamwise distance. This shows preferable configurations with twoinherently stable combustion delivery rates (A and B), and two otherpossible conditionally stable delivery rates (C and D), compared with anunstable delivery rate (E).

For the five cases shown, uncombusted fluid is delivered over a lengthL_(D) into a combustor of length L_(C). The uncombusted fluid isdelivered at a mass flow rate M_(D) per unit length of the combustor.Energetic combustor fluid flows into a region at a mass flow rate M_(E).The uncombusted fluid and energetic fluid mix to form a mixed combustionfluid within the region. Some fuel and oxidant combust in a region,heating the mixed fluid, forming energetic fluid and delivering it intothe next region.

The fluid delivery along the streamwise dimension of the combustor fromthe upstream end to L_(D), the delivery flow ratio R of M_(D) to M_(E)is preferably configured and controlled to be approximately constant inthese configurations. Consequently, these cases are characterized byapproximately exponentially increasing delivery flow rates M_(D) andmass flow rates M_(E). Five different ratios R of mass delivery flowratio of M_(D) to M_(E) are shown, with consequent differences in thetotal quantity of fluid delivered, which is proportional to the areaunder each delivery profile curve.

In each of these five cases, the chemical compositions of the delivereduncombusted fluid mixture are modeled as about the same, resulting inabout the same adiabatic combustion temperature T_(ADIAB). (i.e., thefinal fluid temperature after the uncombusted fluid is caused to befully combusted with no heat loss). In these configurations, the hot orenergetic pilot fluid is preferably delivered into upstream end of theprogressive combustion region. In these models, the hot pilot fluid isassumed to have about the same composition and to be at the adiabaticcombustion temperature T_(ADIAB) that would result from adiabaticallycombusting the delivered uncombusted fluids. The temperatures of thedelivered uncombusted fluids T_(DEL), are preferably lower than theself-ignition temperature T_(IGN) of the combusting fluids.

The neutrally stable configuration B is preferably configured for andcontrolled at about the critical fluid delivery flow ratio R_(CRIT),which by definition separates the inherently stable delivery condition,such as configuration A, from the conditionally stable condition, as inconfiguration cases C and D (in contrast to the unstable configurationE). This critical flow rate ratio R_(CRIT) of Case B is the maximumprogressive flow rate ratio possible which can be maintainedindefinitely in a given configuration. Under such conditions,maintaining the flow rate ratio R_(CRIT) results in an approximatelyexponentially increasing fluid delivery profile. This can be nominallymaintained over an unlimited length of the reactor (beyond L_(D))without quenching combustion at a mean temperature of the mixedcombusting fluid at or greater than T_(CRIT).

For configurations with hot fluid entering the combustion region at atemperature greater than T_(CRIT), progressively delivering uncombustedfluid at the flow ratio R_(CRIT) will maintain the mean mixed combustingfluid temperature greater than or equal to T_(CRIT) (decliningasymptotically towards T_(CRIT) in successive combustion regions). Forhot combustion fluid delivered into one of the combustion regions atT_(CRIT), delivering uncombusted fluid into that and later regions atthe critical fluid delivery ratio R_(CRIT) will maintain the mean mixedfluid temperature at T_(CRIT) in that and successive combustion regions.

Preferably delivering uncombusted fluid in configuration B at thecritical fluid delivery ratio R_(CRIT) under adiabatic combustionprovides the highest sustainable delivery ratio R_(CRIT-Max) to sustainmixed combusting fluid temperature T_(CRIT) when hot fluid is deliveredinto the combustion regions at T_(CRIT). With increasing heat loss tothe surroundings, the uncombusted fluid is preferably delivered at acritical flow delivery ratio R_(CRIT) that is progressively lower thanR_(CRIT-MAX) and which declines in proportion to the heat loss rate.

Some embodiments may be preferably configured and controlled toprogressively deliver uncombusted fluid at a flow ratio R_(PC) less thanthe critical flow rate ratio R_(CRIT) giving an inherently stableconfiguration depicted as case A. For such inherently stableconfigurations A, the combustion fluid temperature is typically greaterthan and approaching a mean temperature of sustained progressivecombustion, T_(PC), which is greater than the equivalent mixed fluidtemperature for the critical case T_(CRIT) at the critical flow rateratio R_(CRIT) With preferable configurations like A, if the hot fluidenters a combustion region at T_(PC), then delivering uncombusted fluidat the ratio R_(PC) above R_(CRIT) will maintain the fluid temperatureat T_(PC).

To preferably maintain the combustion fluid at a mixed fluid temperatureT_(PC) above the mean fluid critical temperature T_(CRIT), at least therate of diluted fuel-oxidant mixture is preferably controlled tomaintain the fluid deliver ratio R_(PC) less than the correspondingcritical delivery flow rate ratio R_(CRIT) of delivered fluid mass flowrate to hot combustor fluid flow rate.

For inherently stable configurations A or the neutrally stableconfiguration B, the hot combustion fluid temperature exiting one ormore combustion regions is preferably controlled to be at least greaterthan or equal to T_(CRIT) by configuring and controlling the uncombustedfluid deliver rate ratio at a level that is less than or equal toR_(CRIT). In such preferable inherently or neutrally stableconfigurations, combustion provides specific molar heat release rates(by combustion of the combustible gases per minimum stoichiometry ofmaterial) that deliver heat at about equal to the rate of enthalpychange due to formation of the products of combustion relative to theuncombusted fluid, plus the rates of enthalpy absorbed by any diluents(including diluents within the fuel and oxidant mixture, any diluentfluids added, and any oxidant fluids or fuel fluid in excess of thestoichiometric ratio) plus any rates of net heat loss (or minus any heatgain) from the surrounding walls, regions, and upstream and downstreamcombustion regions.

These models assume continuous delivery, or pseudocontinuous deliverythrough numerous orifices, with corresponding rapid mixing. Realcombustor may have more discrete flows and slower mixing rates.Accordingly, configurations are preferably configured to control flowdelivery ratios in a range from a lower ratio to an upper ratio. Thisresults in the combusting fluid temperature being controlled between alower and an upper mixed fluid temperature.

For example, fluid delivery ratio is preferably controlled betweenR_(PC) and ratio R_(CRIT) to preferably control the mean combustingfluid temperature in an inherently stable sustainable fashion betweenT_(PC) and T_(CRIT). Since the allowable flow delivery ratio is zero atT_(ADIAB), the flow delivery ratio R_(PC) is preferably controlled toless than 90% of the range between T_(CRIT) and T_(ADIAB). For higherinherently sustainable flows, the ratio R_(PC) is preferably controlledbetween 33% and 99% of R_(CRIT) and more preferably between 67% and 95%of R_(CRIT).

In some configurations, the fluid delivery may be configured forconditionally stable operation by providing an uncombusted delivery flowdelivery ratio R_(CS) greater than the critical flow delivery ratioR_(CRIT). Such higher flow delivery rates R_(CS) result in conditionallystable combustion as exhibited in cases C and D or in eventuallyunstable combustion as shown in configuration E of FIG. 8. Progressivelydelivering fluid at the fluid delivery ratio R_(CS) results in anexponentially increasing fluid delivery profile that would eventuallyquench the combustion process. Mixing cooler delivered uncombustedfluids with the combusting fluid at such delivery ratios R_(CS) coolsthe combustion toward the temperature of the delivered uncombustedfluids, T_(DEL). This eventually drops the combusting fluid temperaturebelow the ignition temperature T_(IGN) as depicted in FIG. 8 case E.

With further reference to FIG. 8, in configurations with conditionallystable delivery rates R_(CS) above R_(CRIT) has reduced the fluidtemperature below T_(CRIT) the uncombusted fluid delivery is preferablystopped or more preferably reduced to below R_(CRIT) while the mixtureof uncombusted and combusting fluid is still above its self-ignitiontemperature. E.g., to R_(PC). This allows the combustion process to berejuvenated to a higher temperature, preferably above T_(CRIT).Configurations are preferably configured and controlled to at leastavoid letting the temperature of progressive combustion fall below theself-ignition temperature T_(IGN). (i.e., the blowout condition shown incase E). In such a blowout condition, there is little or no possibilityof the combustion process being rejuvenated after the end of uncombustedfluids delivery. Such blowout conditions are preferably avoided tosustain stable combustion in the present invention.

When the progressive delivery of uncombusted fluid is stopped inconditionally stable configurations such as C and D, the temperature ofthe hot combusting fluid system will rise toward the adiabaticcombustion temperature, T_(ADIAB). When the progressive delivery isreduced from R_(CC) to a fluid ratio R_(PC), the combustion fluidtemperature will rise back towards T_(PC). As desired, combusting fluidtemperatures generally below T_(CRIT) may conditionally maintained byalternating fluid delivery rates between levels above and belowR_(CRIT). This is preferably combined by weighting the relative durationof the higher and lower flow rates. E.g., the time at R_(CC) relative totime at R_(PC).

With further reference to the conditionally stable cases C and D of FIG.8, when the combustion process are rejuvenated, a configuration mayprovide for the end of the combustor to occur before full fuelconversion is approached. In such cases D, CO concentrations remainrelatively high. E.g., above about 100 ppmv. In other configurations,the combustor is preferably extended to provide further residence timeand burnout of unburned hydrocarbons and CO, as shown in configurationC. e.g., with CO below about 10 ppmv. This distinguishes betweenconditionally stable combustion with burnout as in case C, versus aconditionally stable configuration without burnout as in case D.

In some configurations, one or more of the delivery flow ratio orcomposition of fluid delivered into a region may be desirably controlledto adjust the adiabatic temperature of the mixed composition in one ormore regions. For example, the adiabatic temperature may be constrainedto limit formation of combustion byproducts such as NOx, as depicted inFIG. 13 by staying outside of the lower central region.

Similarly, the delivery flow ratio or fluid delivery composition may becontrolled to adjust the mixed fluid composition within one or moreregions. For example, configurations may be desirably configured forrich combustion or partial oxidation as shown in FIG. 15. In suchsystems, the oxidant/fuel ratio is configured to below thestoichiometric ratio. This oxidant/fuel ratio Lambda is preferablyconfigured above the coke or soot formation level. E.g., Lambda >0.5 or0.6. More preferably, both the water/fuel and air/fuel ratios areadjusted to constrain soot formation below a desired level.

With further reference to conditionally stable cases C, D (or theunstable case E), while unlimited exponentially increasing deliverywould eventually quench the combustion process, in some configurationsthe delivery profile may be configured with multiple delivery regionsinterrupted by periods of lower delivery ratios less than R_(CRIT), orno delivery. During the periods of lower or no delivery ratios, thecombustion process is allowed time to rejuvenate, thus keeping thesystem within a pseudo stable state. This is analogous to discretestaged Progressive Combustion, in that delivering a finite amount offluid at each delivery location is nominally similar to having arelatively high fluid delivery ratio. However, when the amount added ateach location is constrained and has a finite rate of mixing with thecombusting fluid, this is like interrupting delivery or spreading outthe fluid delivery preventing the combusting fluid temperature frombeing reduced to quenching conditions.

To control the temperature within a range that is bounded by a lowertemperature below T_(CRIT) (and above T_(IGN)) the flow rate ispreferably controlled in a time weighted combination of delivery flowratios both above and below R_(CRIT). E.g. between a range from 25% to150% of R_(CRIT). The delivery flow ratio of uncombusted fluid to hotcombustion fluid may similarly be controlled such that the progressivestreamwise integral from an upstream region inlet to a downstream regionis at least greater than the delivery flow ratio required to maintainignition. Preferably the delivery flow ratio is maintained to provide atemperature about 33% of the way between the ignition temperatureT_(ING) and the adiabatic combustion temperature T_(ADIAB).

Preferably this streamwise integral of the delivery flow ratio iscontrolled within a range about the corresponding progressive streamwiseintegral for the respective critical flow delivery ratios in thecombustion regions. Controlling the flow delivery ratio may similarly beused to control the fluid temperature within a temperature range aboutthe critical temperature T_(CRIT). Where fluid delivery compositionvaries in the streamwise direction, this integral will further accountfor such variations and the corresponding changes in the ignitiontemperature, adiabatic temperature, and critical temperature, andcorresponding critical delivery flow ratio. More preferably, thisstreamwise integral of the delivery flow ratio is maintained at lessthan or equal to the streamwise integral of the critical delivery flowratio sequentially within each region. This maintains inherently stablecombustion.

To increase combustion stability of a Progressive Combustion system forthe same amount of fluid delivered, some configurations preferablyreduce the rate of delivery and distribute it over a longer length ofthe combustor both with continuous or staged-discrete delivery. Thismethod of delivering fuel, oxidant and diluent fluids is complemented bycontrolling for other methods. For example, these additional concernspreferably include one or more of (1) the degree of combustionstability, (2) controlling pollutant removal such as CO, (3) controllingpollutant formation such as NOx, (4) controlling the adiabatictemperature of the diluted mixture, and (5) the overall constraint onthe physical size of system.

FIG. 9 graphically depicts the results of some time-based numericalequilibration regimes. These simulations show the effects of a range ofequilibration region temperature control methods on the concentrationsof CO and Nitric Oxide (NO) in the combustion product fluid after theprimary combustion region. NO is shown as representative of all theoxides of nitrogen (NOx). These results are numerical computationsutilizing the comprehensive iso-octane oxidation mechanism published byCurran et al. (2002).

The combustible fluid modeled comprises iso-octane as fuel fluid, andair as the oxidant fluid provided in about a 5% excess of stoichiometricflows. Water is preferably used as diluent fluid. E.g., being set atabout 3.15 times the fuel mass. Primary combustion is modeled asoccurring at about 30 atm. At the end of the combustion period, thecombustion product fluids are at 1500° C.

About 1 ms after the final quantities of uncombusted fluid is deliveredto the combustor, the combusting fluid reaches a nominallypost-combustion state at the beginning of the equilibration region. Herethe CO concentration is about 28 ppm and the NO concentration is about1.6 ppm.

To demonstrate the impact of some embodiments of controllingequilibration conditions, a variety of temperature controls areimplemented after 1 ms for an equilibration period, while maintainingthe pressure at about 30 atm. For these models, temperature controls maynominally be implemented by isobarically transferring energy to or fromthe system.

In configurations A, B, C and D, the equilibrating fluid temperature isnominally changed or stepped very rapidly from 1500° C. to about 900°C., 1100° C., 1200° C. and 1300° C., each step being followed by anequilibration residence time in an equilibration region in which thetemperature is held about constant. By comparison, in configurations Eand F, the equilibration temperature first steps very rapidly to 1300°C. followed by a more gradual decrease in the equilibration temperature.The temperature profiles in the cases E and F are shown as aboutlog-linear with temperature declining linearly versus log-time.

With further reference to the lower graph in FIG. 9, the correspondingCO concentration responses are shown for these configurations. For thetemperature step-isothermal configurations A, B, C and D, the CO removalrate immediately after the step is highest in case D with the hottestisotherm at 1300° C., and lowest in case A with the coldest isotherm at900° C. Intermediate configurations B and C have intermediate rates.

Configurations A, B, C and D, show that while higher temperaturesinitially favor higher CO removal rates, higher temperatures also resultin higher CO equilibrium levels. This is due to greater dissociation ofcarbon dioxide at higher temperatures. For example it may take over 20ms for CO concentrations to be reduced to approximately 3 ppmv at 900°C., while it may only take about 1 ms at 1300° C. However, after about100 ms at 1300° C., the CO concentration remains its equilibrium valueof about 3 ppmv. By contrast, for the 900° C. case, the CO concentrationafter 100 ms may drop over 100 times to about 8 ppbv while approachingits equilibrium level of near 3 ppbv.

Changes in NO concentration for several different temperature controlsare also shown in FIG. 9. For the cases shown, the NO concentration ofabout 1.5 ppm that was established further upstream during the primarycombustion process at 1500° C., was not significantly changed during anyof the subsequent equilibration temperature controls methods.

With continued reference to FIG. 9, cases E and F demonstrate otherequilibration temperature profiles (apart from step-isotherm sequences)that result in faster responses in CO concentration reduction to targetlevels. The factor of improvement in response time generally increaseswith lower final temperatures or lower target CO levels. For example,for a CO target level of about 1 ppm a gradually decreasing temperatureprofile of condition E results in the realization of the target COconcentration in about 85% of the time it would take for the beststep-isothermal option.

For a target CO of about 0.2 ppmv, case E is able to reduce the time toapproximately 75% of the best step-isothermal option. In keeping withthis trend, for 10 ppbv, case F reduces the response time to about 40%of the best step-isothermal option. The slower temperature gradient caseF initially drops the CO rate slower than the faster gradient case E.However to achieve lower CO emissions lower than 10 ppbv, there comes atime when the slower gradient F reduces CO emissions faster than case E.

The desired emissions levels may be adjusted according to pertinentregulations. E.g. 50 ppmvd, 25 ppmvd, 9 ppmvd, or 2.7 ppmvd, convertedto a 15% O₂ basis. More preferably, the emissions with power systems arepreferably configured to an output based parameter. E.g. NOx massemissions per shaft power out: <500 mg/GJ for <3 MWe; <240 mg/GJ, andfor 3 MWe to 20 MWe and <120 mg/GJ for >20 MWe. For more stringentemissions, these levels could be reduced to about 0.032 kg/MWhe.

In comparing the benefits of temperature steps and the greater benefitsof temperature gradients, more preferred embodiments may be configuredwith a continuous curvilinear variation in the temperature gradient.“For a given fluid composition, there may be a preferred fluidtemperature which gives a more rapid rate of decline in COconcentrations. i.e., a higher temperature would result in slower rateof CO reduction due to higher carbon dioxide dissociation, while a lowertemperature would give a slower rate of CO oxidation reaction. Inconsidering a streamwise sequence of fluid compositions, there may be apreferred local fluid temperature gradient which gives a preferred COoxidation rate for the locally changing fluid composition.”

Accordingly, a hypothesized embodiment may be configured for an optimumtemperature profile, which continuously optimizes the local temperaturegradient. This lowers the temperature with increasing residence time,thus optimizing the CO oxidation rate. Such a method may result in acompact embodiment, reducing CO more rapidly to target levels. Thishypothesized embodiment is schematically estimated and shown asconfiguration G in FIG. 9.

This time-dimensional perfectly mixed analysis may readily be extendedto two and three dimensional models to provide more realistic spatialand temporal distributions. The configuration method is preferablyadjusted to accommodate the increased times required for realcombustion, turbulence, mixing and evaporation rates. These improvedresults may be used to refine the equilibration methods described abovee.g., of using sequential or progressive equilibration regions withstepped, ramped or continuously varying temperatures, temperatureranges, or temperature profiles optionally coupled with one or moreequilibration volumes and residence times.

With reference to FIG. 10, some configurations may control one or bothof the temperature and residence times of the equilibration regionswhile accounting for the water to oxygen ratio in the energeticcombustor fluid. FIG. 10 schematically approximates control methodsshowing desired CO concentration versus the suggested equilibrationtemperature for the water-diluent system as modeled in FIG. 9. Similarcontrol methods, approximately graphically parallel to the relationshipsof FIG. 10, may be applied for different combustion systems comprisingcarbon-based fuels, and various oxidant and diluent fluids. Asdemonstrated in less-water/more-air and more-water/less-air cases, ifexcess air displaces water as the primary diluent, the suggestedequilibration temperature is higher for a given target CO concentrationand vice versa.

For the configuration modeled in FIG. 10, the combustion product fluidsmay be brought to near the equilibration temperatures corresponding tothe target CO levels indicated in the figure. This may use one or moreof the equilibration configuration methods described above to approachthe desired temperature profile. With further reference to FIG. 10,similar relationships between the best equilibration temperature and thedesired emissions concentration at a given residence time may beobtained for mixed fluid diluents comprising air and water or similarfluids with other fluids comprising one or more of nitrogen, water,carbon dioxide and/or oxygen. Generally speaking, as water or steamdisplaces excess air as a primary diluent, target CO levels may beachieved at lower temperatures.

One or more of 1) diluent addition, 2) heat exchange, 3) flowacceleration, and/or 4) expansion or work extraction may be used incontrolling the temperature of the equilibrating fluid within one ormore equilibration regions. For example, FIG. 12 conceptually depicts avariety of sets of embodiments for temperature control in equilibrationregions, using one. These control methods are conceptually depicted ascovering temperature regions such as 900° C., 1100° C., 1300° C., 1500°C. and 1700° C., within the range of turbine inlet temperatures thatcharacterize current and future levels of turbine technologies.

Each of these temperature control methods may be utilized individuallyor in any combination with any of the others, at any of these or othertemperature ranges. The diluent addition and/or heat exchange methodsare nominally shown as being variously applicable to the fulltemperature range. While it may be used at lower temperatures, theexpander method, FIG. 11, is shown as being capable of handling higherturbine inlet temperatures such with energetic fluids in advancedturbines at about 1700° C. At such temperatures, the equilibrium COconcentrations are substantially higher than the desired system exitconcentrations.

Accordingly the temperature reductions and efficiencies desiredpreferably involve utilizing expanders with one or more equilibrationregions after the first and/or subsequent expander(s) where temperaturesare appropriate for the equilibration and residence time desired toachieve the desired reductions in CO emissions. Where multiple turbinestages are used to reduce the energetic fluid temperature from theturbine inlet temperature (TIT) to the desired lowest equilibrationtemperature (e.g. from 1500° C. to 1200° C.), then multipleequilibration regions are preferably used over a single stepequilibration region. These can be configured for faster equilibrationand thus shorter and more compact equipment than a single step.Downstream equilibration regions are preferably longer than the intakeresidence times.

FIG. 11 shows a representative embodiment of a gas turbine powergenerating system utilizing the Progressive Combustion and Equilibrationstrategies to control emissions. This uses a combustor 1 comprising a(contiguous) primary combustion region 3 and an optional equilibrationregion 4 as described in FIG. 1. This embodiment may use one or moreinterstage equilibration regions 5 within the turbine to further reduceCO concentrations at the lower temperatures resulting from partialexpansion of the combustion gases.

Progressive combustion as described in conjunction with FIG. 1 occurs inthe ‘primary combustion region’ 3 a portion of the combustor 1. Thesource for the oxidant fluid F1 may be a blower, a compressor or acompressor system 63. For example, uncompressed air F6 may be modified,humidified, enriched with oxygen, or diluted, prior to, during, or aftercompression. This may include wet compression with a water mistentrained into the compressor inlet, or delivered within the compressor.Exhaust gas may also be recirculated and compressed along withatmospheric air F6. As discussed in FIG. 1, other inputs to the primarycombustion region 3 include one or more fuel fluids F2 and one or morediluent fluids F3.

Combustion product fluids from the primary combustion region 3 may passthrough one or more optional equilibration regions 4-5, where COconcentrations are reduced by controlling one or more of the fluidtemperature, and/or residence time (as discussed above). Further oxidantF1 or diluent F3 may be added at this point as part of the temperaturecontrol, and to refine stoichiometry to provide a beneficial oxidantconcentration in the equilibration region.

With reference to FIG. 16, in some embodiments, fluid temperatures at anintermediate region in the power system would result in equilibrium COconcentrations above a desired CO outlet concentration. E.g., at theoutlet of a high pressure combustor feeding hot combustor fluid into theinlet of a turbine. The fluid temperatures would preferably be reducedalong a curvilinear temperature path to provide rapid CO reduction.E.g., a hypothetical path G such as described above and shown in FIG. 9,and in FIG. 16.

As schematically depicted in FIG. 16, expansion through an expansionstage of a work engine is relatively rapid. This configuration nominallyshows hot fluid flowing from an equilibrating region 4 into a turbineinlet with a temperature of about 1400° C. The hot fluid temperature canbe approximated by a step drop in temperature, or preferably as a rapidcurvilinear temperature gradient or profile. E.g., stages 58, 59, 60 ina turbine or reciprocating engine. Where available expansion equipmentexpands the fluid faster than the desired curvilinear temperature path,the temperature may be reduced along a more rapid a curvilinear pathwith one or more expanders to one or more desired holding temperatures.E.g. as shown by path H in FIG. 16 or as in paths C, or D, in FIG. 9. Atleast one of the expansion stages 58, 59, 60 is preferably followed byat least one equilibrating region 5. The volume of the equilibratingregion is preferably configured relative to the fluid flow rate toprovide an equilibrating residence time to further oxidize the CO toCO₂.

For example, with reference to FIG. 11, in some configurations, thepressurized, partially equilibrated combustion gas F13 is expandedthrough a first turbine expander 58, producing partially expandedcombustion gases F14. As is typical in a gas turbine, the first turbine58 may be used, via a shaft 61 or other energy transfer means, to driveone or more compressors 63, and possibly a load such as electricgenerator 55. Some configurations may configure equilibration regionsbetween turbomachinery stages configured along a common shaft. Themechanical shaft power or electrical power produced is preferably usedfor mechanical drive applications or energizing a user load or toconvert electricity to at least one of mechanical power, light, addingheat, or removing heat. This method further uses the power system topreferably transmit the electricity generated over distances exceedingabout 8 km or 5 miles.

Implementing the progressive combustion and equilibration strategiesherein described, may, in some configurations, require a larger thanconventional combustor 1 to provide a greater residence time. Suchlarger residence times may be required with high diluent concentrationswhere the oxidant concentration is preferably reduced to nearstoichiometric concentrations (for example from about 15% excess oxygento about 5% excess oxygen).

The larger compressor combustor 1 may involve a greater separationbetween compressor 63 and first turbine expander 58. In such aconfiguration, one or more additional bearings 56 may be required tocontrol shaft vibrations. A larger thrust bearing or additional thrustbearings 57 may also be required to accommodate a thrust differentialdue to the use of significant quantities of diluent F3 in the combustor1 with correspondingly lower oxidant fluid F1, compared withconventional lean combustion turbines.

Where an equilibration region 5 is configured between two turbineexpansion stages one or more shaft stabilization bearings 56 may beadded to control vibrations of a long shaft 23. e.g., between one orboth of expander stages 58 and 59, and between expander stages 59 and60. These bearings may be mounted on stators between expansion stages.Such bearings 56 are preferably protected from the hot fluid and cooledwith diluent to enable operation near the high temperature flows. Theheated diluent is preferably recycled into the progressive combustionsystem.

As a result of the work extracted in the first turbine expander orexpander stage 58 the partially expanded combustion gas F14 will becooler than the partially equilibrated combustion gases F13 produced bythe combustor 1. The resulting cooler more equilibrated combustion gasesF16 are then preferably expanded through a second turbine expander stage59. These cooler gases may be passed through a second interstageequilibration region 5 within a turbine section for at least a seconddesired interstage residence time. This takes advantage of these lowertemperatures to further reduce the CO concentrations towards the newlower equilibrium CO concentrations at this lower temperature. Thesecond interstage residence time may be larger than the first interstageresidence time to accommodate the slower CO reaction rate at the coolertemperature, depending on the degree of reaction desired relative to thetemperature. In such equilibration regions, at least 75% of thetemperature reduction occurs in less than 50% of the streamwise fluidpath length of that equilibration region.

With reference to FIG. 9, uses an equilibration residence time of atleast 0.5 ms is desired for the reaction at about 1500° C. Consideringconfiguration D, an expansion with temperature drop from 1500° to 1300°C. may use an equilibration residence time of at least 0.7 ms, andpreferably at least 1 ms. Similarly, configurations C, E, F and G mayuse a residence time of at least 1.5 ms, and preferably 3 ms to reducethe CO to below 1 ppmv. These models are for near stoichiometriccombustion. E.g., about 1.05 Lambda. E.g. the NOx output is preferablycontrolled to less than about 2.7 ppmvd at 15% O₂ for combustion systemor to 0.032 kg/MWh in a power system.

This interstage equilibration region 5 may also include a fluid controldevice 10, including the addition of further diluent F15 such aspressurized steam from a Heat Recovery Steam Generator (not shown). Thissecond turbine expander stage 59 may variously be coupled via a powershaft 62 to one or more load devices such as a generator or anothercompressor (not shown). One or more additional turbine expander stages59 as well as other equilibration stages 5 and fluid control devices 11may be included further downstream before combustion gases are fullyexpanded. Some of the remaining thermal energy in the fully expandedcombustion gases F25 may be recovered by producing steam such as with aHeat Recovery Steam Generator (HRSG) (not shown) and/or hot water withan economizer heat exchanger, for use as one or more of the diluent,oxidant or fuel fluids in this system F1, F2, F3, F11, F15, and for useas a diluent F3 or as modifier of the oxidant fluid F1 or the fuel fluidF1.

Again with reference to FIG. 12, the flow acceleration methods oftemperature control are nominally shown to cover moderate to hightemperatures where they are most effective. (They could also be used atlower temperatures.) As noted, the flow acceleration and expandermethods can be used together as well as with diluent cooling and/or heatexchange methods. Such a heat exchanger preferably provides at least 10%of the temperature reduction provided in the equilibration regions. Suchheat exchangers preferably use diluent to remove the heat. The heateddiluent is then preferably delivered upstream into the progressivecombustion or equilibration regions. It may be delivered downstream intoan equilibration region.

The internal volume of each of these equilibration regions may furtherbe individually configured to adjust the residence time undergone by theequilibrating fluid within each of those equilibration region. E.g., thecross sectional area and flow length. Existing residence time betweenone or more expansion stages is preferably accounted for whenconfiguring the additional volume desired for the residence timedesired. For example, in many turbines, an aerodynamic member iscommonly provided to redirect the expanded flow to one or both of apreferred direction and a preferred velocity. The residence time of thefluid passing through such stators or vanes is preferably accounted forand subtracted from the desired residence time when configuring theadditional residence volume.

The residence time provided after cooling with the expander ispreferably at least 50% of the residence time of the fluid expandingthrough the expander stage. In some configurations, the residence timeis preferably at least 175% of the turbine transit time. This preferablyincludes and is greater than the flow time through any stator or vane.

The temperature and/or residence times in the individual equilibrationregions may further be configured in various combinations to achieve thedesired concentrations of one or more species within the energetic orworking fluid discharged from the energy-conversion system. Similarsystems may be configured to control one or more intermediate productsor by-products in the reaction fluids of other reactive systems.

Expansion through an expansion stage of a work engine, such as a turbine58 or reciprocating engine, is relatively rapid and can be approximatedby a step drop in temperature or rapid temperature gradient, orpreferably as a rapid curvilinear temperature profile. Distributeddiluent mist delivery, mixing and evaporation, steam delivery or fluidacceleration may similarly provide relatively rapid temperaturereduction. Conductive heat transfer may be used for more gradualtemperature reduction. These methods may be combined to provide multiplecooling and equilibration methods.

FIG. 13 schematically shows the implications of various mixtures of air,a typical hydrocarbon fuel, and water/steam on a combustion process. Forillustrative purposes and in accordance with the state-of-the-artcatalytic emissions reduction, desired emissions levels for NOx and COare assumed to be at or below 1 ppmv. (Note the concentrations shown areat the nominal outlet concentration. To compare with other applications,these concentrations would need to be converted such as to a dry ppmvd15% O₂ basis or mg/GJ output or lb/MWhe output. A 1 ppmv NOx emissionnear 1.05 relative air/fuel ratio Lambda compares to about 3 ppmvconverted to a 15% O₂ basis.) The temperature of the ProgressiveCombustion region is schematically shown as correlating to the stabilityof the system, since higher temperatures maintain higher reactivities inthe combusting gas.

The diagram nominally identifies a reference water-to-fuel ratio, W₀,which corresponds to the water-to-fuel ratio preferable to give a flametemperature of approximately 1600° C. For different unburned mixtures,this value of W₀ varies, being generally higher as the temperature ofunburned fluid mixture is higher, and as the energy density of the fuelis higher. A W₀ coinciding with a flame temperature of 1600° C. isdepicted here as a reference state, 1600° C. being an approximately thehottest mean temperatures likely to be produced in the combustor ofconventional metal-based gas turbines. Hotter temperatures may be usedwith ceramics.

With continued reference to FIG. 13, the highest flame temperaturetypically coincides with lower quantities of diluent. In the system ofFIG. 13, this diluent may be in the form of water/steam, excess air, orexcess fuel. Consequently, the flame temperature isotherms increase intemperature as they approach the zero-water (W=0), stoichiometric(Lambda=1) condition.

NOx formation in combustion systems is generally promoted by highertemperatures (typically above about 1400° C.) and the presence of oxygenand nitrogen. Accordingly, in FIG. 13, the conditions for significantNOx formation is generally for lower diluent levels which support highertemperatures, while being generally skewed to lean conditions where moresubstantial quantities of molecular oxygen and nitrogen from excess airare present.

Generally speaking, greater than stoichiometric amounts of oxygensupport the oxidation of CO to CO₂ such that CO concentration mayapproach ppm levels. Consequently lean conditions (i.e. Lambda >1) arepreferable for reducing CO concentrations to or below ppm levels. Theequilibrium concentration of CO increases above 1 ppm as systemtemperatures increase above about 1200° C. to 1400° C. In FIG. 13, thisboundary is schematically shown as the upper-temperature boundary of theCO removal region. Since lower temperatures support lower equilibriumconcentrations of CO, the lower-temperature boundary of the CO removalregion is defined by condition wherein temperatures are too low tosupport high-enough kinetic rates to the lower CO equilibriumconcentration levels. With continued reference to FIG. 13, if more timeis allowed for equilibration at lower temperatures, thelower-temperature boundary of the CO removal region shifts to lowertemperatures. About a ten-fold increase in available residence timetypically results in about a 100° C. increase in the minimum temperaturetypically provided to reduce CO concentrations to about 2 ppm levels orless. Possible equilibration operating regimes to control COconcentrations are shown for possible residence times of 10 ms, 100 ms,and one second.

FIG. 13 shows that numerous fluid composition paths may be used tocontrol emissions to desired levels while satisfying stabilityconstraints. For example, a system configured only for high-stabilitymay have high NOx. The method of performing progressive combustionfollowed by equilibration is a suggested way of addressing thesemultiple demands. By passing the combusting/combusted fluids through asequence of conditions during a single combustion process, more than oneemission target may be met.

As an example, FIG. 13 shows two example sequences of methodsdemonstrating this strategy. In case A, slightly lean wet progressivecombustion may be followed by final water to achieve CO equilibrationconditions. (e.g., 1.0<Lambda<1.1) Here, Progressive Combustion mayfirst be performed at 1400° C., as shown at location “PC-A”. After allof the fuel and air, with some water, is added in this ProgressiveCombustion region, the resulting combusted gas is maintained at thiscondition for a first equilibration period. This preferably provides ahigh degree of removal of UHCs and “above-equilibrium” CO levels. Thisequilibration period is identified as “EQ1-A”.

While a temperature of about 1400° C. is below temperatures of high NOxproduction, it is outside the conditions desired to provide very low COlevels. Consequently, the hot fluid is preferably cooled with moreresidence time to reduce the CO. e.g., more water may be added,establishing a new gas temperature of about 1200° C. Providingsufficient residence time may bring the gas to a condition that reducesCO concentrations to below about 1 ppm, “EQ2”. According to theestablished criteria, the gas is best held at condition “EQ2” for a COreduction dwell time of about 10 ms or more. If the product gases are tobe employed at a lower temperature (for example in a turbine systemwhere the TIT less than about 1200° C.), more water might then be addedafter the second equilibration period “EQ2”. The gas may be expandedthrough a turbine.

FIG. 14 shows the results of a numerical simulation of an example ofthis strategy. Fluid delivery during progressive combustion is heremodeled as linear and distributed or as pseudo discrete using numerousorifices. During the period of progressive combustion, “PC-A”, thetemperature of the combusting mixture is maintained below about 1400° C.due to the continual presence of incompletely combusted fuel, maintainedby the constant delivery of uncombusted mixture. For similar reasons, COand UHC levels may have high concentrations. E.g., on the order of 100ppmv. After progressive combustion, further residence time is preferablyprovided for burnout and gas equilibration. e.g., Equilibration orburnout region “EQ1-A”, wherein rates of CO and UHC removal areinitially very high. UHC concentrations are preferably decreased throughseveral orders of magnitude within the burnout region. E.g., to sub-ppblevels. CO concentration also drops and approaches equilibrium after avery short time in the burnout region. E.g., it may equilibrate to about10 ppmv after about 1 ms.

In configurations such as depicted in FIG. 13, and FIG. 14, water and/orsteam diluent is preferably delivered into the hot fluid downstream ofprimary combustion using one or more of the technologies incorporated byreference. E.g., water or steam are preferably delivered through one ormore perforated tubes positioned transversely to the fluid flow. Thisdiluent delivery is preferably configured and/or controlled to providedesired transverse temperature profiles in the hot combustion fluidexiting the combustor. Alternatively orifices or nozzles in combustorwalls may be used as exemplified in the patents to Ginter.

With continued reference to FIG. 13, “PC-B” identifies a preferred casein which Progressive Combustion is allowed to occur under slightly richconditions (0.9<Lambda<1.0). This is preferably followed by anequilibration or burnout region “EQ2-B.” More oxidant and diluent arepreferably delivered to establish the second equilibration conditions“EQ2”. These are preferably delivered through nozzles or orifices aboutperforated tubes or walls as described by the technology incorporated byreference. The amount of oxidant delivered is preferably sufficient tochange the oxidant/fuel ratio by at least 2%. This preferably pushes thestoichiometry from the rich region with insufficient oxidant to combustall the fuel, to the region region with an excess of oxidant.

Simulation results of such a preferred rich to lean configuration areshown in FIG. 15. The low availability of oxygen under the richconditions results in less NOx being formed compared to progressivecombustion under slightly lean conditions. High concentrations of UHCare present in the first equilibration burnout region “EQ1”. Howeverthese are light molecules, typically methyl species, which are quicklyoxidized in the second equilibration region “EQ2”. This exemplary richto lean method results in about 20% to 40% less NOx than the case forprogressive combustion under slightly-lean conditions for the conditionschosen.

Many similar reaction paths incorporating such Progressive Combustionand Equilibration methods may be applied in different configurations asbest suits the goals of the designer.

Progressive Reactions and Equilibration

Various embodiments of the progressive combustion and equilibrationmethods described may be beneficially used to conduct a variety ofchemical and biochemical reactions, especially exothermic reactions.Configurations similar to the embodiments described above may be usedwith a reactant fluid comprising a reactant instead of fuel fluid.Similarly, a co-reactant fluid comprising a co-reactant may be usedinstead of the oxidant fluid. A diluent fluid comprising one or morecompounds suitable to dilute the exothermic reaction while notinterfering with the desired reaction or causing excessive byproducts ispreferably used. These may include hydrocarbons or other non-aqueouschemicals for non-aqueous reaction systems. The thermo-spatialequilibration methods including work extraction described toprogressively reduce CO emissions may similarly be used to progress theprimary reaction between reactants and reduce intermediate reactionproducts. The thermo-spatial methods used to constrain byproductformation, such as NOx, may similarly be used to constrain undesiredreaction byproducts.

Such methods preferably control the streamwise rate of diluted reactablefluid delivery to desirably constrain streamwise composition andtemperature within desirable ranges to maintain stable reaction rates,progress the reaction to reduce intermediate products, and constrainresidual byproducts. These thermo-spatial configuration and controlmethods improve product quality and value. They improve the rate atwhich reactants can be processed, and provide more compact components.The work extraction methods exemplified may be used to further recoverenergy and reduce processing costs.

The reactions are preferably conducted to reduce intermediate productsto a concentration less than or equal to 100 ppmv. The temperature ofthe hot fluid is preferably constrained to below 1700° C. at the exit ofone of the reaction regions or to similar temperatures. E.g., at theinlet to an expander. Temperatures within reaction regions may also bepreferably controlled to similar temperatures.

Hot fluid is preferably delivered to the inlet of the reactor toinitiate the reaction and bring it to a desired reaction temperatureaccording to the respective chemical process. E.g., the fluids may beheated to a temperature where the reaction is at least 200% greater thanthat with reacting fluids at ambient conditions.

For example, such progressive reactions and chemical equilibration mayinclude, but are not limited to: alkylations, carbonylations,carbamylations, chlorination, direct oxidations, ethoxylations,halogenations, hydroformylations, hydrogenations, nitrations, solutionpolymerizations, sulfations, and sulfonations. Such diluted progressivereactions may be used to prepare a wide variety of chemicals,biochemicals and foods. These may include, but are not limited to: asurfactant, a demulsifying agent, an emulsifying agent, a hydrocarbonfuel, a synthetic lubricant, a halogenated hydrocarbon, a hydrocarbonsolvent, an organic polymer, a fire retardant, a fabric treatment agent,an antibiotic, an antiviral agent, an anti-pathogenic agent, afungicide, a herbicide, an insecticide, a pesticide, a rodenticide, afood product, and the like.

Various embodiments may be used to prepare the following chemicals:ethanol from ethylene, ethylene oxide by oxidation of ethylene, ethyleneamines from ethylene oxide, ethylene glycol by oxygenating ethylene,ethanol amines from ethylene dichloride, hydrogen peroxide usinganthraquinone; maleic anhydride, n-butanephenol from propylene andbenzene, adipic acid from phenol, caprolactam from cyclohexane,cyclohexanol from benzene, ethylene glycol ethyl ethers, chloroaceticacid from acetic acid, propylene oxide, n-Butanol from propylene,acrylic acid from propylene, tetrahydrofuran from maleic acid, andn-Butyl acrylate by esterfying acrylic acid. The emulsifying agents orsurfactants may include: alkyl benzene sulfonates, linear alkylbenezenesulfonates, secondary alkane sulfonates, ester sulfonates, alpha olefinsulfonates, alkyl glyceryl ether sulfonates, alkyl glyceryl sulfonates,methyl ester sulfonates, natural fat sulfonates, natural oil sulfonates,alcohol sulfates, alcohol ether sulfates and the like.

Other embodiments preferably utilize the methods described herein and inthe technology incorporated by reference to controllably mix fluids andconduct endothermic reactions. These may include delivering heateddiluents to add heat to the system, increase the reactants' temperatureand promote the reaction.

Generalization

From the foregoing description, it will be appreciated that a novelapproach for mixing, delivering and reacting three or more fluids tocontrolling emissions or components from intermediate or byproductreactions has been disclosed using one or more methods described herein.This method of controlling emissions may be applied to a broad range ofcombustion systems such as including gas-turbines, internal combustionengines, furnaces, burners, process heaters, incinerators, flares, andsubterranean combustors.

The flows and/or composition of the associated fuel, oxidant and diluentfluids may be varied to achieve a desired chemical composition orcomposition range of the working or energetic fluid, to control orreduce intermediate and/or byproduct emissions. The kinetic andthermodynamic principles herein applied to controlling UHC, CO & NOxemissions can, by extension, be applied to the control of other chemicalspecies present in the energetic or working fluid of a combustionsystem, chemical refining process, or other chemical reaction orprocessing system.

While the components, techniques and aspects of the invention have beendescribed with a certain degree of particularity, it is manifest thatmany changes may be made in the specific designs, constructions andmethodology herein above described without departing from the spirit andscope of this disclosure.

Where dimensions are given they are generally for illustrative purposeand are not prescriptive. Of course, as the skilled artisan willappreciate, other suitable sizes, orientations, configurations anddistributions of fluid delivery orifices, fluid passages, and othercomponents may be efficaciously utilized, as needed or desired, givingdue consideration to the goals of achieving one or more of the benefitsand advantages as taught or suggested herein.

Where combustor, mixing chambers and orifice delivery configurations areprovided, similar two or three dimensional configurations orcombinations of those configurations may be efficaciously utilized,including varying the nominal thicknesses, diameters, cross sectionalshapes, spacings, orientations, and other dimensions and parameters forthe combustor walls, mixing chambers and orifices. Additionalequilibration regions may be added or configured in the combustion orreaction system to control intermediate or byproduct species as desiredor needed. E.g., by controlling one or more of the carbon, oxygen,hydrogen, and nitrogen compositions. Where fluid delivery refers togases, it will be appreciated that the fluids may comprise liquid spraysor mists.

Where the terms fuel, reactant, diluent, water, carbon dioxide, air,oxygen, oxidant, and co-reactant have been used, the methods aregenerally applicable to other combinations of those fluids or to othercombinations of other reacting and diluent fluids. Concentrations ofother elements such as sulfur, phosphorus, halogens, noble gases, andselected metals or ceramics may also be controlled.

Where fluid quantities are referred to, these methods are generallyapplicable to include quantities delivered at multiple times, and tocontinuous fluid flows. Where assembly methods are described, variousalternative assembly methods may be efficaciously utilized to achieveconfigurations to achieve the benefits and advantages of one or more ofthe embodiments as taught or suggested herein.

Where transverse, axial, radial, circumferential or other directions arereferred to, it will be appreciated that any general coordinate systemusing curvilinear coordinates may be utilized including Cartesian,cylindrical, spherical or other specialized system such as an annularsystem. Similarly when one or more transverse or axial distributions orprofiles are referred to, it will be appreciated that the configurationsand methods similarly apply to spatial control in one or morecurvilinear directions as desired or prescribed.

While the components, techniques and aspects of the invention have beendescribed with a certain degree of particularity, it is manifest thatmany changes may be made in the specific designs, constructions andmethodology herein above described without departing from the spirit andscope of this disclosure.

Various modifications and applications of the invention may occur tothose who are skilled in the art, without departing from the true spiritor scope of the invention. It should be understood that the invention isnot limited to the embodiments set forth herein for purposes ofexemplification, but includes the full range of equivalency to whicheach element is entitled.

COMPONENT LIST 1 Combustor 2 Combustion Chamber 3 Primary CombustionRegion 4 1st Equilibration Region or Burnout Region 5 2ndEquilibration/Interstage Region 6 Premixing Region 7 Common PremixingRegion 8 Premix-Combustion Walls 9 Premix-Premix Walls 10 1stEquilibration Fluid Control Device 11 2nd Equilibration Fluid ControlDevice 12 Perforated Pilot Fire Tube 13 1″ Fire Tube 14 2″ Fire Tube 153″ Fire Tube 16 4″ Fire Tube 17 Pilot Mixture Inlet 18 Stage 1 MixtureInlet 19 Stage 2 Mixture Inlet 20 Stage 3 Mixture Inlet 21 Plenum Cap 221″ Fire Tube Plate 23 2″ Fire Tube Plate 24 3″ Fire Tube Plate 25 4″Fire Tube Plate 26 Pilot Plenum 27 Stage 1 Plenum 28 Stage 2 Plenum 29Stage 3 Plenum 30 Pilot Igniter Orifices 31 Pilot Combustion regionOrifices 32 Stage 1 Orifices 33 Stage 2 Orifices - Set 1 34 Stage 2Orifices - Set 2 35 Stage 2 Orifices - Set 3 36 Stage 3 Orifice - Set 137 Stage 3 Orifice - Set 2 38 Stage 3 Orifice - Set 3 39 PilotCombustion region 40 Stage 1 Combustion region 41 Stage 2 Combustionregion 42 Stage 2 - Set 1 Micro Region 43 Stage 2 - Set 2 Micro Region44 Stage 2 - Set 3 Micro Region 45 Stage 3 Combustion region 46 Stage3 - Set 1 Micro Region 47 Stage 3 - Set 2 Micro Region 48 Stage 3 - Set3 Micro Region 49 Igniter (Glow Plug) 50 Electric Power Source 51Igniter Flange 52 Thermal Mass Flame Holder 53 Insulation 54 TurbinePower System 55 Electric Generator 56 Thrust Bearings 57 AdditionalBearings 58 Turbine1 59 Turbine2 60 Turbine3 61 Shaft1 62 Shaft2 63Compressor F1  Oxidant Inflow to Combustor F2  Fuel Inflow to CombustorF3  Diluent Inflow to Combustor F4  Uncombusted Inflow to Combustor F5 Uncombusted Inflow to Pilot F6  Uncompressed Oxidant/Air F7  PremixFluids F8  Pilot Fluids F9  Combustor Fluid Flow F10 EnergizedCombustible Fluids F11 1st Equilibration Delivery Fluids F12 CombustorProduct Fluids before 1st equilibration F13 Combustor Product Fluidsafter 1st equilibration F14 Combustor Product Fluids before 2ndequilibration F15 2nd Equilibration Delivery Fluids F16 CombustorProduct Fluids after 2nd equilibration F17 Combustor Product Fluidsbefore 3rd equilibration F18 3rd Equilibration Delivery Fluids F19Combustor Product Fluids after 3rd equilibration F20 Pilot to Stage 1Flow F21 Stage 1 to Stage 2 Flow F22 Stage 2 to Stage 3 Flow F23 Stage 3to Burnout Flow F24 Burnout to Exhaust Flow F25 Fully Expanded Gases

What is claimed is:
 1. A method of reducing pollutants within a hotreaction fluid formed by reacting reactant fluid comprising a reactantwith oxidant fluid comprising an oxidant, diluted by diluent fluidcomprising a diluent, within a reaction system having an upstreamprimary reaction region and a downstream equilibration system having afirst equilibration region; the method comprising: generating hotreaction fluid within the primary reaction region; equilibrating the hotreaction fluid within the equilibration system for a residence timegreater than a prescribed residence time; and reducing the temperatureof the hot reaction fluid within the equilibration system to less than aprescribed temperature at the system outlet; wherein configuring thefluid composition, temperature, residence sequential flow profilesufficiently: to reduce the volume concentration of unreacted reactantcomponents in the hot reaction fluid at the system outlet to less than25 pmvd at a 15% O₂ basis; to reduce the volume concentration ofresidual dissociated reaction product in the hot reaction fluid at thesystem outlet to less than 25 pmvd at a 15% O₂ basis; and to constrainthe volume concentration of byproduct oxidation components formed withinthe reaction system to less than 25 ppmvd at a 15% O₂ basis at thereaction system outlet.
 2. The pollutant reduction method of claim 1wherein the reaction comprises combustion, of fuel fluid comprising afuel, with oxidant fluid comprising oxygen, diluted by diluent fluidcomprising one of water and carbon dioxide, within a combustion systemhaving an upstream primary combustion region and a downstreamequilibration system having a first equilibration region; the methodcomprising: generating hot combustion fluid within the primarycombustion region; equilibrating the hot combustion fluid within theequilibration system for a residence time greater than 0.5 ms; reducingthe temperature of the hot combustion fluid within the equilibrationsystem by at least 5° C. to less than 1700° C. at the system outlet;wherein configuring the fluid composition, temperature, residencesequential flow profile sufficiently: to reduce the volume concentrationof unburned hydrocarbons (UHC) in the equilibrated reaction fluid at thesystem outlet to less than 25 pmvd at a 15% O₂ basis; to reduce thevolume concentration of residual carbon monoxide (CO) in theequilibrated fluid at the system outlet to less than 25 pmvd at a 15% O₂basis; and to constrain the volume concentration of byproduct nitrogenoxides (NOx) formed within The equilibration system to less than 25ppmvd at a 15% O₂ basis at the system outlet.
 3. The method of claim 2,wherein reducing the fluid temperature comprises flowing diluent fluidcomprising added water through an inlet to said equilibration region. 4.The method of claim 3, wherein the equilibration residence time of hotcombustion fluid in the system increased to accommodate longerequilibration rates for cooler fluids and lower residual oxidant, thanwith equivalent systems configured for diluents not comprising water. 5.The method of claim 3, wherein the mass delivery flow rate of wateradded to said equilibration system is greater than 1% of the hotcombustion fluid flow.
 6. The method of claim 2, wherein the increase involume concentration of byproduct NOx within the equilibration system isless than 3 ppmvd at a 15% O₂ basis.
 7. The method of claim 2, whereinvolume concentration of carbon monoxide (CO) exiting the equilibrationsystem is less the CO concentration entering the equilibration system.8. The method of claim 2, wherein the residual volume concentration ofcarbon monoxide (CO) exiting the equilibration system is less than 5ppmvd at a 15% O₂ basis.
 9. The method of claim 1, wherein equilibratingthe hot reaction fluid comprises providing a burnout period to oxidizeunreacted reactant components to below a prescribed level.
 10. Themethod of claim 1, wherein the primary reaction system comprises aplurality of primary reaction regions in streamwise sequence, thereaction regions having a critical temperature T_(CRIT) at which thereaction is neutrally stable between a self-ignition temperature T_(IGN)and an adiabatic temperature T_(ADIAB) bounding stable and conditionallystable regions, the method comprising the steps of: flowing unreactedoxidant, fuel, and diluent fluids into the plurality of primary reactionregions at respective mass delivery flow ratios of unreacted fluids tohot reaction fluid, whereby forming a plurality of mixed hot reactionfluids, controlling the mass flow delivery ratios to between 0.25 and1.50 times the critical delivery flow ratio R_(CRIT) for each of saidprimary reaction regions; controlling the mean temperature of the mixedhot reaction fluid in each of said regions above its ignitiontemperature and below the adiabatic temperature of oxidant and fuelcombustion; controlling one of the composition and the temperature ofthe fluids delivered to said regions to maintain the combustiontemperature of the hot reaction fluid exiting the most downstream ofsaid regions to less than 1700° C.; characterized in that the volumeconcentration of byproduct reaction components produced by the method isless than 25 ppmvd at a 15% O₂ basis.
 11. The method of claim 10,wherein controlling the temperature in said plurality of combustionregions to within 33% and 67% of the temperature range between theignition temperature and adiabatic reaction of said fluid as it exitssaid plurality of reaction regions by one of controlling the massdelivery flow ratio, controlling the amount of diluent, controlling theamount of air, and controlling the amount of fuel.
 12. The method ofclaim 10, wherein controlling fluid delivery to maintain said massdelivery flow ratio R to less than the critical delivery flow ratioR_(CRIT) in said plurality of regions; and maintaining the temperatureof the hot reaction fluid in said plurality of regions to greater thanor equal to the critical temperature T_(CRIT).
 13. The method of claim10, wherein the step of controlling the temperature, includescontrolling a temperature in a region within a range including at leastsome time below the critical temperature T_(CRIT) by controlling themass delivery flow ratio within a range including at least some timeabove the critical delivery flow ratio R_(CRIT).
 14. The method of claim10, wherein controlling the temperature comprises increasing thetemperature of the hot reaction fluid in one of said plurality ofregions by decreasing said mass delivery flow ratio into said region toa level lower than the critical delivery flow ratio R_(CRIT), when thetemperature of the hot reaction fluid entering the region is less thanthe critical temperature T_(CRIT).
 15. The method of claim 10, whereincontrolling the temperature comprises decreasing the temperature of thehot reaction fluid in one of said plurality of regions by increasingsaid mass delivery flow ratio into said region to a level higher thanthe critical flow ratio R_(CRIT), when the temperature of the hot fluidentering the region is greater than the critical temperature T_(CRIT).16. The method of claim 10, comprising flowing diluent fluid andreactant fluid into one of said regions with a mass delivery flow ratioof diluent to fuel of 150% or more.
 17. The method of claim 10, whereinadding unreacted fluids to said plurality of regions comprisescontrolling the delivery of unreacted fluid into the plurality ofregions such that a progressive streamwise integrated delivery flowratio of said fluid is less than or equal to the progressive integratedcritical delivery flow ratio R_(CRIT) for the corresponding fluidcompositions.
 18. The method of claim 10, wherein controlling the meanfluid temperature in the plurality of regions by controlling the diluentmass delivery flow rate relative to the reaction heat released withinthe plurality of regions.
 19. The method of claim 10, wherein deliveringfluids to the reaction regions comprises changing the oxidant toreactant ratio in the mixed reaction fluid from an excess of reactant inan upstream reaction region to an excess of oxidant in a downstreamreaction region.
 20. The method of claim 1, wherein the temperature ofthe equilibrated hot reaction fluid as it exits the reaction system iscontrolled to less than about 1300° C. and greater than about 800° C.21. The method of claim 1, wherein equilibrating the hot reaction fluidcomprises delivering and mixing oxidant fluid with the hot reactionfluid in the equilibration region.
 22. The method of claim 1, whereincontrolling the delivery of oxidant fluid and reactant fluid into saidprimary combustion region such that the ratio of oxidant to fuel is lessthan the stoichiometric ratio.
 23. The method of claim 1, wherein atleast 75% of said temperature reduction occurs in less than 50% of thestreamwise fluid path length of said equilibration region.
 24. Themethod of claim 1, wherein reducing the temperature during equilibrationby greater than 100° C.
 25. The method of claim 1, comprisingcontrolling delivery of fuel, oxidant, and diluent fluids toprogressively combust fuel under fuel “rich” conditions whilecontrolling composition to operate within a combustion stabilityboundaries and below byproduct or NOx production boundaries.